1. Field of the Invention
The invention relates to a sealing ring to be applied to connection holes of the cells of an accumulator.
2. The Prior Art
As is known, electrical accumulators substantially consist of a container made from polypropylene equipped on the inside with a plurality of divider walls. The walls define cells inside in which the elements of the accumulator and the electrolyte are arranged.
The elements consist of a plurality of plates arranged interfacing each other and electrically and mechanically connected through connection rods made from lead, known as straps.
The rods of the adjacent elements with opposite polarity are connected together through openings consisting of connection through holes with a frusto-conical cross-section made on the divider walls.
The electromechanical connection is obtained by welding, making an electrical current of an intensity such as the make the parts in contact melt pass through the rods.
To avoid the electrolyte flowing from one cell to the other and to avoid the divider wall being damaged during welding, an insert is used, known as a sealing ring.
The sealing ring comprises a circular plate equipped with a through hole axially to which is arranged a cylindrical sheath with a diameter equal to the connection hole and a length equal to or less than the thickness of the divider wall.
The ring is coupled in the connection hole and is generally made from polycarbonate, which as known has a higher melting point than that of polypropylene.
The sheath being placed between the divider wall and the connection rods prevents the wall itself from melting during welding.
The circular plate which is placed in contact with the divider wall carries out the function of a gasket and ensures the airtight seal of each cell.
A first drawback of the described sealing ring consists of the fact that the coupling with the connection hole is not stable and is not very reliable.
This is substantially due to the fact that both the sealing ring and the connection hole are obtained by moulding or punching and therefore have dimensional tolerances such as not to guarantee an ideal coupling.
Another drawback linked to the previous one consists of the fact that the sealing ring must be inserted manually and contextually to the arranged of the elements. This is to avoid the ring accidentally detaching from the wall.
A further drawback consists of the fact that the contact region between the cylindrical sheath and the surfaces of the connection hole is limited to an annular region near to the plate.
This is substantially due to the fact that, as stated previously, the sheath has a circular cross-section whereas the connection hole has a frusto-conical cross-section.
Another drawback linked to the previous one consists of the fact that the limited contact surface between sheath and the surfaces of the connection hole does not allow an ideal dissipation of the heat which develops during the welding of the rods. Moreover, the heat concentrating in the annular contact region can compromise the airtight seal of the cell.
The purpose of the present invention is to overcome these drawbacks.
In particular, a first purpose of the invention is to provide a sealing ring which stably coupled with the connection hole.
A further purpose is to provide a ring which can be inserted in the corresponding connection hole even automatically and at a different time to the insertion of the elements of the accumulator.
Another purpose is to provide a sealing ring which allows a better dissipation of the heat which develops during the welding of the rods.
A further purpose is to provide a ring which is cost-effective and which can be provided by moulding.
The last but not least purpose is to provide a protective ring which does not require specific tools for insertion in the corresponding connection hole.